1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2011-23393 discloses a process of performing rear surface grinding on a substrate bonded to a wafer support system (hereinafter may be referred to as “WSS”) through a light-to-heat conversion film (hereinafter may be referred to as “LTHC film”). Supporting a substrate by a WSS in this way enables the handling of the substrate after it is thinned to a thickness on the order of several tens of μm.
The inventor has investigated the technology of Japanese Patent Laid-Open No. 2011-23393, and the following problem has been found.
If the substrate is bonded to WSS, an outer circumference of the substrate is a little ground, thereby reducing the diameter of the substrate so that it is smaller than the diameter of WSS. For example, if the diameter of the substrate is 300 mm, the substrate is ground to the diameter of 298.5 mm. As a result, it is possible to prevent the substrate from being misaligned with the WSS when bonded thereto, or an adhesive agent from running off out of the WSS. Moreover, it is possible to reduce the degree of the outer circumference of semiconductor substrate 2 after grinding becoming knife-edged.
However, as described above, when the diameter of the substrate is smaller than the diameter of WSS, as illustrated in FIGS. 21 and 22 of Japanese Patent Laid-Open No. 2011-23393, the LTHC film is exposed on the surface of WSS at the substrate side. The LTHC film may contain an organic substance or metal. In this case, the subsequent process proceeds while the LTHC film is exposed in region close to the substrate, it was found that LTHC film-derived contaminants occur on the surface of the substrate.
In particular, the inventor has investigated a method of manufacturing a semiconductor device which comprises through silicon via (hereinafter, through silicon via may be referred as “TSV”). In this method, the protective film needs to be formed on the ground surface of the substrate after grinding the substrate. Therefore, when the protective film is formed with the wafer surface of the substrate contaminated, contaminants are hard to be removed by subsequent cleaning.
In this way, it was found that in the method of manufacturing a semiconductor device including the step of grinding the substrate bonded to WSS through LTHC film, the method has room for improvement in terms of reducing the contaminants.